铁道建筑

针对铁路工程沿线隧道洞渣产量大和天然河砂资源匮乏的现状，采用铁路隧道施工现场的花岗岩、片麻岩、白云岩洞渣加工成机制砂及碎石骨料，制备高强度C60混凝土，开展不同岩性洞渣混凝土微观结构对宏观力学性能影响研究。采用扫描电镜（Scanning Electron Microscope,SEM）和X射线计算机断层扫描（X-ray Computed Tomography,X-CT）图像分析法，测定三种岩性洞渣混凝土的微观形貌、孔结构及界面过渡区特征，通过力学性能对比分析微观结构参数对抗压、抗折强度的影响。结果表明：片麻岩洞渣混凝土孔隙率较低，初期界面过渡区结构较好，水化初期强度增长较快，但孔隙率及界面过渡区结构随龄期增长变化较小，水化后期强度增长较慢，骨料中裂隙较多，骨料强度较低，最终强度较低；花岗岩和白云岩洞渣混凝土随龄期增长孔隙率和界面过渡区结构得到优化，强度增长较快。白云岩洞渣混凝土中大尺寸（大于1 500μm）孔径孔隙率较高，但孔隙形态规则，多为球形，对强度影响较小。

In response to the high production of tunnel slag and the scarcity of natural river sand resources along railway engineering lines, high-strength C60 concrete was prepared by processing granite, gneiss, and Baiyun cave muck from railway tunnel construction sites into machine-made sand and crushed stone aggregates. The influence of the microstructure of different rock lithologies of tunnel muck concrete on macroscopic mechanical properties was studied.Scanning Electron Microscope(SEM) and X-ray Computed Tomography(X-ray CT) image analysis methods were used to determine the microstructure, pore structure, and interfacial transition zone characteristics of three rock lithologies of tunnel muck concrete. The influence of microstructural parameters on compressive and flexural strength was analyzed by comparing mechanical properties. The results show that the porosity of gneiss tunnel muck concrete is low, the interfacial transition zone structure is well-developod, and the strength increases rapidly in the early stage of hydration.However, the porosity and interfacial transition zone structure change little with age, and the strength increases slowly in the later stages of hydration. There are many cracks in the aggregate, and the aggregate strength is low, resulting in a lower final strength. The porosity and interfacial transition zone structure of granite and Baiyun cave slag concrete are optimized with increasing age, and the strength increases rapidly. The large pore size, which is greater than 1500 μm, in the Baiyun cave slag concrete has a high porosity. But the pore morphology is regular, mostly spherical, and has little effect on the strength.